The Litmus collators retain all necessary information to collate and execute transactions to create an unsealed block and provide it, together with a proof of state transition, to one or more relaychain validators responsible for proposing a parachain block.
Collators will also watch the progress of block-producing and consensus protocols in BABE and build on what they think is the latest relay chain block that will be finalised. Collators do not directly participate in the consensus for the relay chain and therefore never stake DOT.
To become a collator and start to author blocks, one has to possess a valid session key, which is either set in the initial genesis config as invulnerables or by selection via the cumulus collator-selection pallet.
Currently, to keep it simple and focus on product development, we are running collators with our own nodes for Litmus. However, we are not ruling out the possibility to invite third-party or the community to join our collator set when we think the time is right.